diff --git a/fpdfsdk/fpdf_edittext.cpp b/fpdfsdk/fpdf_edittext.cpp
index 56ea16a..6e9a586 100644
--- a/fpdfsdk/fpdf_edittext.cpp
+++ b/fpdfsdk/fpdf_edittext.cpp
@@ -849,8 +849,9 @@
   return FPDFFontFromCPDFFont(pTextObj->GetFont());
 }
 
-FPDF_EXPORT unsigned long FPDF_CALLCONV
-FPDFFont_GetFamilyName(FPDF_FONT font, char* buffer, unsigned long length) {
+FPDF_EXPORT size_t FPDF_CALLCONV FPDFFont_GetFamilyName(FPDF_FONT font,
+                                                        char* buffer,
+                                                        size_t length) {
   auto* cfont = CPDFFontFromFPDFFont(font);
   if (!cfont) {
     return 0;
@@ -861,7 +862,7 @@
   ByteString name = cfont->GetFont()->GetFamilyName();
   pdfium::span<const char> name_span = name.span_with_terminator();
   fxcrt::try_spancpy(result_span, name_span);
-  return static_cast<unsigned long>(name_span.size());
+  return name_span.size();
 }
 
 FPDF_EXPORT FPDF_BOOL FPDF_CALLCONV FPDFFont_GetFontData(FPDF_FONT font,
diff --git a/public/fpdf_edit.h b/public/fpdf_edit.h
index 9669b36..2c758f3 100644
--- a/public/fpdf_edit.h
+++ b/public/fpdf_edit.h
@@ -1377,8 +1377,9 @@
 // Regardless of the platform, the |buffer| is always in UTF-8 encoding.
 // If |length| is less than the returned length, or |buffer| is NULL, |buffer|
 // will not be modified.
-FPDF_EXPORT unsigned long FPDF_CALLCONV
-FPDFFont_GetFamilyName(FPDF_FONT font, char* buffer, unsigned long length);
+FPDF_EXPORT size_t FPDF_CALLCONV FPDFFont_GetFamilyName(FPDF_FONT font,
+                                                        char* buffer,
+                                                        size_t length);
 
 // Experimental API.
 // Get the decoded data from the |font| object.